The present invention relates to flame ignition of a gaseous fuel burner, particularly to ignition of plural fuel burners employed in a range.
Historically, plural range burners were ignited by a central standing pilot flame via flash tubes channelled from the standing pilot to the individual burners. However, in recent times, it has been desired to eliminate a standing pilot flame and to employ electric spark ignition of the individual burners. Typically, where it is desired to provide spark ignition of plural burners on a range, the spark igniter was centrally located and ignited individual burners via flash tubes connecting the central spark igniter with the individual burners. For safety reasons and for economies of manufacture, it has been desired to eliminate the use of flash tubes for plural burner ignition and most recently, ranges have utilized individual spark electrode sets disposed adjacent each burner.
Where individual spark electrodes have been provided adjacent each one of a plurality of burners, it has been common practice to provide the high voltage to a pair of the electrode sets by a common connection to a single secondary winding of a step-up transformer employed for generating the high voltage to create the spark.
Referring to FIG. 3, a typical prior art plural burner spark ignition system is illustrated where a pair of spark electrodes for igniting a pair of burners is indicated generally at 10 and 12 with each of the pairs having a pointed electrode 11,13 respectively, and a flat electrode 15,17 respectively. The pointed electrodes 11,13 are each attached to an opposite end of transformer secondary coil 14. The flat electrodes 15,17 are commonly grounded.
A second pair of burner ignition electrodes indicated generally at 16,18 is also typically employed for igniting a second pair of burners and each has a pointed electrode 19,21 respectively and a flat electrode 23,25 respectively disposed oppositely thereto. Each of the pointed electrodes 19,21 is connected to one opposite end of a second transformer secondary winding 20. The flat electrodes 23,25 are commonly grounded with electrodes 15,17 of the first pair 10,12. The secondary transformer windings 14,20 have a common transformer primary winding 22 which receives a pulse from the capacitive discharge circuit indicated generally at 24.
It will be seen from the prior art circuit arrangement of FIG. 3 that the current in the secondary windings flows in a common direction as indicated by the counter-clockwise arrows and the character "I". This prior art circuit arrangement results in a positive polarity at the pointed electrodes 11,19 and a negative polarity at the point of the electrodes 13,21. This type of spark discharge arrangement has been found to have the disadvantage that the flat electrodes 17,25 do not have a predominantly strongly positive point thereon and experience an unpredictable electric field pattern within the gap area and a random spark discharge in an erratic direction at times. Where the spark energy is reduced, such as by deterioration of the circuit components, or by low line voltage, such an arrangement may even prevent a spark from occurring at either burner electrode within the pair.
Thus it has been desired to find a way or means of providing a high energy spark discharge between a pair of electrodes adjacent a fuel burner utilizing the maximum commonality of transformer winding connections and to provide such a spark system with a reliable and repeatable high energy concentrated spark discharge for igniting gaseous fuel.